Trust in one's fellow citizens and in politicians are both conducive to well-functioning government. Beyond their separate importance, it is a long-standing notion that generalized social trust and political trust are connected in a mutually reinforcing relationship that further undergirds democratic governance. While it is well established that social trust and political trust are robustly positively associated at the individual level, there is much less compelling evidence regarding the causal nature of this relationship. Previous analyses have been unable to adequately rule out confounding and correct for reverse causality. This paper tackles these challenges through data and a research design close to ideally suited for addressing the causal status of the relationship. Using a 20-wave individual-level panel survey from Sweden analyzed using a dynamic panel model, we find evidence for a relatively strong positive causal effect of political trust on social trust, but little evidence for the reverse relationship.